Drill bits are commonly used for drilling bore holes or wells in earth formations. One type of drill bit is a fixed cutter drill bit which typically includes a plurality of cutting elements, or cutters, disposed within a respective cutter pocket formed within one or more blades of the drill bit.
FIG. 1A shows a perspective view of a drill bit 100, or fixed cutter drill bit 100, in accordance with the prior art. FIG. 1B shows a profile of the drill bit 100 of FIG. 1 in accordance with the prior art. Referring to FIGS. 1A and 1B, the drill bit 100 includes a bit body 110 that is coupled to a shank 115 and is designed to rotate in a counter-clockwise direction 190. The shank 115 includes a threaded connection 116 at one end 120. The threaded connection 116 couples to a drill string (not shown) or some other equipment that is coupled to the drill string. The threaded connection 116 is shown to be positioned on the exterior surface of the one end 120. This positioning assumes that the drill bit 100 is coupled to a corresponding threaded connection located on the interior surface of a drill string (not shown). However, the threaded connection 116 at the one end 120 is alternatively positioned on the interior surface of the one end 120 if the corresponding threaded connection of the drill string, or other equipment, is positioned on its exterior surface in other exemplary embodiments. A bore (not shown) is formed longitudinally through the shank 115 and extends into the bit body 110 for communicating drilling fluid during drilling operations from within the drill string to a drill bit face 111 via one or more nozzles 114 formed within the bit body 110.
The bit body 110 includes a plurality of gauge sections 150 and a plurality of blades 130 extending from the drill bit face 111 of the bit body 110 towards the threaded connection 116, where each blade 130 extends to and terminates at a respective gauge section 150. The blade 130 and the respective gauge section 150 are formed as a single component, but are formed separately in certain drill bits 100. The drill bit face 111 is positioned at one end of the bit body 110 furthest away from the shank 115. One or more of the plurality of blades 130 are either coupled to the bit body 110 or are integrally formed with the bit body 110. The gauge sections 150 are positioned at an end of the bit body 110 adjacent the shank 115. The gauge section 150 includes one or more gauge cutters (not shown) in certain drill bits 100. The gauge sections 150 typically define and hold the entire hole diameter of the drilled hole. A junk slot 122 is formed, or milled, between each consecutive blade 130, which allows for cuttings and drilling fluid to return to the surface of the wellbore (not shown) once the drilling fluid is discharged from the nozzles 114 during drilling operations.
A plurality of cutters 140 are coupled to each of the blades 130 within a respective cutter pocket 160 formed in the blade. The cutters 140 may be formed in an elongated cylindrical shape or other shapes. Each cutter 140 typically includes a cutting surface 144, and a portion of the cutter 140 including the cutting surface 144 extends outwardly from the blade 130 from within the respective cutter pocket 160. The cutter 140 is positioned within the pocket 160 such that the cutting surface 144 extends outwardly from the top section 154 of the blade 130. The cutting surface 144 can be formed from a hard material, such as bound particles of polycrystalline diamond forming a diamond table. In some embodiments, a line 180 (shown FIG. 1B) connecting the outer most tip of each cutter 140 of the drill bit 100 represents the profile of the drill bit 100.
Each blade 130 includes a leading section 152, a top section 154, and a trailing section 156. The top surface 154 extends from one end of the trailing section 156 to an end of the leading section 152. The leading section 152 faces in the direction of rotation 190. Each blade 130 also includes transition sections 158. Transition sections 158 extend between the top section 154 and the leading section 152. Each individual transition section 158 is between two adjacent cutter pockets 160. Each transition section 158 has a curvature that generally has a radius of larger than 5 millimeters.
During some drilling operations (e.g., drilling operations that involve relatively high instantaneous rate of penetration (ROP)), the depth of cut (DOC) resulting from the drilling by the drill bit may be significantly greater than the exposure of the cutters of the drill bit. A DOC that is greater than the exposure of the cutters may indicate that the blade of the drill bit may also be cutting and/or pushing earth formation as the drill bit rotates. Thus, it may be desirable to improve the cutting efficiency of the blade.